The present invention relates generally to a pulse detonation system for a gas turbine engine and, in particular, to a pulse detonation system which is able to replace the core of a gas turbine engine and separately power the fan and booster compressor thereof.
One type of pulse detonation system which has eliminated the need for a separate valve is disclosed in a patent application entitled “Pulse Detonation Device For A Gas Turbine Engine,” having Ser. No. 10/383,027 now U.S. Pat. No. 6,928,804, and being owned by the assignee of the present invention. It will be noted therein that the pulse detonation device includes a stationary air inlet duct and a ring member which rotates therearound. The various events of the detonation take place within detonation ducts associated with the ring member, as air and fuel are injected and a detonation wave is initiated therein. In this configuration, the aft portion of the rotatable ring member is connected to a drive shaft in a cantilevered manner. The air ports, fuel injectors and initiation devices are located adjacent an outer surface of the air inlet duct so as to be sequentially aligned with an inner end of the detonation ducts, which are open at each end, as the ring member rotates.
A second type of pulse detonation system owned by the assignee of the present invention is disclosed in a patent application entitled “Rotating Pulse Detonation System For A Gas Turbine Engine” having Ser. No. 10/422,314, now U.S. Pat. No. 6,931,858. This system discloses a rotatable cylindrical member having a forward surface, an aft surface, and an outer circumferential surface, where a plurality of spaced detonation passages are disposed therethrough. In particular, each detonation passage includes at least a portion thereof with a longitudinal axis extending therethrough oriented at a circumferential angle to a longitudinal centerline axis through the gas turbine engine. The pulse detonation system also includes a shaft rotatably connected to the cylindrical member and a stator is configured in spaced arrangement with the forward surface of the cylindrical member and a portion of the shaft. The stator further includes at least one group of ports formed therein alignable with the detonation passages as the cylindrical member rotates. In this way, detonation cycles are performed in the detonation passages so that combustion gases exit the aft surface of the cylindrical member to create a torque which causes the cylindrical member to rotate.
Another pulse detonation system owned by the assignee of the current invention is disclosed in a patent application entitled “Rotary Pulse Detonation System With Aerodynamic Detonation Passages For Use In A Gas Turbine Engine,” having Ser. No. 10/803,293. The pulse detonation system described therein includes a rotatable cylindrical member having a forward surface, an aft surface, and an outer circumferential surface, where at least one stage of circumferentially spaced detonation passages are disposed therethrough. Each detonation passage further includes: a leading portion positioned adjacent the forward surface of the cylindrical member, with the leading portion having a centerline therethrough oriented at a designated angle to an axis extending substantially parallel to the longitudinal centerline axis within a specified plane; a trailing portion positioned adjacent the aft surface of the cylindrical member, with the trailing portion having a centerline therethrough oriented at a designated angle to the axis within the specified plane; and, a middle portion connecting the leading and trailing portions, with the middle portion having a centerline therethrough with a substantially constantly changing slope in the specified plane. A shaft is rotatably connected to the cylindrical member and a stator is configured in spaced arrangement with the forward surface of the cylindrical member and a portion of the shaft. The stator further includes at least one group of ports formed therein alignable with the leading portions of the detonation passages as the cylindrical member rotates. In this way, detonation cycles are performed in the detonation passages so that combustion gases interact therewith to create a torque which causes the cylindrical member to rotate.
While the configurations disclosed by the foregoing patent applications are useful for their intended purpose, it will be seen that in each case a single drive shaft is powered by the particular pulse detonation system. This drive shaft is connected to both the fan section and the booster compressor in a high bypass type gas turbine engine. Due to the high inertia characteristics of the fan, the starting torque required for it is much greater than that for the booster compressor. Thus, the starting systems designed to provide such starting torque are generally larger and less economical than if the booster compressor was started separately from the fan.
Accordingly, it would be desirable for a pulse detonation system to be developed for a gas turbine engine which is able to operate the engine without the need for a separate valve. Further, it would be desirable for such pulse detonation system to be modified so that it is able to separately start the booster compressor from the fan of the gas turbine engine.